Aim To study the effect of monocyte chemoattractant protein-1(MCP-1) and 17-β-estradiol(E₂) on the expression of lymphocyte function associated antigen-1(LFA-1), scavenger receptor(SR) and apolipoprotein E(apoE) by monocytes. Methods THP-1 cells (a human acute monocytic leukemia cell line) were cultured for the experiments. The protein expression of LFA-1 and SR on THP-1 cells were assayed by indirect immunofluorescence combined with flow cytometry and confocal laser scanning microscopy respectively. The monoclonal antibody of SR was 2F8(rat anti mouse macrophage SR). The mRNA expression of SR and apoE in THP-1 cells was determined by reverse transcription-PCR(RT-PCR). Results MCP-1 could stimulate the expression of LFA-1 on THP-1 cells, the positive cell rate in MCP-1 group and control group were 66.1%±2.5% and 43.3%±3.7% (P<0.01), the mean fluoresence intensity(MFI) were 221.3±17.8 and 132.8±18.7 respectively (P<0.01). The positive cell rate and MFI in MCP-1+ E₂ group were 59.5%±2.1% and 204.2±22.5 (P<0.05 versus MCP-1 group), respectively. MCP-1 also stimulated the protein expression of SR on THP-1 cells, the net fluoresence intensity(NFI) in MCP-1 group and control group were 48.9±9.8 and 32.5±3.2 respectively (P<0.01), the NFI in MCP-1+ E₂ group were 49.7±10.4 (P>0.05 versus MCP-1 group). The RT-PCR also showed that MCP-1 could induce the mRNA expression of SR on monocytes, but doesn’t have obvious effects on apoE expression. [WT5”HZ]Conclusions By increasing the expression of LFA-1 on monocytes, MCP-1 can promote the monocyte-endothelium adhesion. MCP-1 also induces the expression of SR on monocytes, but doesn′t have obvious effects on apoE expression, therefore